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LINE-1 Methylation Analysis in Mesenchymal Stem Cells Treated with Osteosarcoma-Derived Extracellular Vesicles
Published on: February 1, 2020
Quantitative analysis of promoter hypermethylation in multiple genes in osteosarcoma
1Chien-Shiung Wu Laboratory, Department of Biological Science and Medical Engineering, Southeast University, Nanjing, China.
Background:
Osteosarcoma is the most common solid malignant diseases of childhood, occurring in approximately 6 children per million annually; however, to the authors' knowledge to date, the cause of osteosarcoma has remained mostly unknown. Genetic alterations of genes that are specific for osteosarcoma have not been identified. Genetic alternations in the status of DNA methylation, known as epigenetic alterations, are the most common molecular alterations in human neoplasia. Aberrant methylation in the promoter region of tumor-related genes is associated closely with epigenetically mediated gene silencing, which is a common feature in human tumors.
Methods:
The authors analyzed CpG islands of 5 different gene loci for aberrant methylation profiles in 30 pairs of osteosarcoma and corresponding normal tissues by using the quantitative methylation-specific polymerase chain reaction method. The objectives of this study were to characterize the methylation changes in osteosarcoma more extensively and to identify epigenetic biomarkers that may be useful in the diagnosis and prevention of osteosarcoma.
Results:
For the Ras effector homologue (RASSF1A), tissue inhibitor of metalloproteinase 3 (TIMP3), O-6-methylguanine DNA methyltransferase (MGMT), and death-associated protein kinase 1 (DAPK1) genes, significant differences were observed in the degree of hypermethylation between tumors and normal tissues (P < 0.01 and P < 0.001, respectively). Measurement of the cumulative multiple promoter hypermethylation revealed striking differences between tumor specimens and normal tissues (t = 7.31; P < .001). There also was a significant difference in the levels of DNA methylation between the metastatic and nonmetastatic high-grade osteosarcomas (t = 4.57; P < .01). In addition, the methylation levels were associated closely with gender (t = 6.44; P < .001).
Conclusions:
The results indicated that tumor tissues from patients with osteosarcoma had a significantly higher incidence of hypermethylation for several genes compared with corresponding normal tissues. The epigenetic changes observed in this study may have prognostic importance for patients with osteosarcoma.
Insights
Epigenetic alterations, specifically DNA hypermethylation in genes like RASSF1A and TIMP3, are significantly increased in osteosarcoma tumors compared to normal tissues. These findings suggest potential prognostic biomarkers for this childhood bone cancer.
Area of Science:
- Oncology
- Epigenetics
- Molecular Biology
Background:
- Osteosarcoma is a common childhood malignancy with largely unknown causes.
- Epigenetic alterations, particularly DNA methylation changes, are prevalent in human cancers.
- Aberrant promoter methylation can lead to gene silencing in tumors.
Purpose of the Study:
- To extensively characterize methylation changes in osteosarcoma.
- To identify potential epigenetic biomarkers for osteosarcoma diagnosis and prevention.
Main Methods:
- Analysis of CpG islands in 5 gene loci from 30 osteosarcoma/normal tissue pairs.
- Quantitative methylation-specific polymerase chain reaction (PCR) was employed.
Main Results:
- Significant hypermethylation was observed in RASSF1A, TIMP3, MGMT, and DAPK1 genes in tumor tissues.
- Cumulative promoter hypermethylation showed striking differences between tumor and normal tissues.
- DNA methylation levels differed between metastatic and non-metastatic osteosarcomas and were associated with gender.
Conclusions:
- Osteosarcoma tissues exhibit a significantly higher incidence of gene hypermethylation compared to normal tissues.
- Observed epigenetic changes may hold prognostic value for osteosarcoma patients.
